What To Do If You Have a Sewer Backup

Who to Contact in Case of a Sewer Backup

If you experience sanitary sewer backup issues and suspect the cause is not the result of a blockage or defect with your private sanitary sewer lateral, please contact our Department of Public Works at 414-302-8800 (7 a.m. to 3 p.m. Weekdays).  If your issue happens outside of these hours, you can contact the Non-Emergency Police Department number at 414-302-8000 and they will dispatch a City of West Allis Sewer Crew to verify the City’s Sewer Main is flowing.  By calling us first, you may save yourself a plumbing bill.

If you experience a sanitary sewer issue during dry weather, it is highly likely that it's the result of a blockage or defect with your private sanitary sewer system.  In these cases, we recommend you contact a licensed plumber to help you identify and remediate the issue.  

This chart shows what to do in the event of a sanitary sewer backup.

Sewer Backup Flowchart (PDF)

Your lateral may be eligible for a lateral rehab reimbursement program. Please contact the Engineering Department for more information.

If you have a sanitary sewer backup, please also go to the MMSD sewer backup site to report this issue.

MMSD Sewer Backup Site

A reminder from our Engineering staff: just because something can be flushed, doesn't mean it should be. Paper towels, napkins, etc. do not disintegrate. You may be creating costly clogs in your pipes & our community sewer pipes. Learn what NOT to flush.


Your home’s plumbing is connected to the public wastewater system through an underground pipe called a "private sewer lateral." As the property owner, you own this pipe and are responsible for keeping it flowing freely and repairing cracks and breaks. Laterals do not necessarily end at the curb or property line, but extend all the way to the public sewer main, which often is located in the middle of the street. The City maintains the public sewer.

A diagram of typical sewer lateral in West Allis is shown here: Sewer Lateral Diagram (PDF)


These steps can help you reduce the risk of the unpleasant and usually costly experience of a sewage backup in your home.

  • Televising your service is the best way to determine the condition of your entire lateral. A video inspection may reveal cracks, breaks, offsets, and root intrusion. The pipe may need to be cleaned, repaired, or replaced.
  • If you have large trees growing near your sewer lateral, you may want to use a root treatment periodically to make sure your lateral is not becoming blocked. Root treatment can be purchased at most hardware and home improvement stores. You may also need to hire a pipe cleaning specialist or a plumber to remove the roots completely.
  • Do not pour fats, oil or grease down drains. Pour into a coffee can or similar container, allowing them to cool and solidify, and deposit in the trash. Do not dispose of coffee grounds or other heavy solids down the drain.
  • Do not flush wipes, diapers or feminine hygiene products, even if they are labeled "flushable." As homes age, roots often infiltrate sewer laterals. So-called flushable products catch on these intrusions, or on grease build-up, and form clogs. (Watch videos from Consumer Reports and the Water Environment Federation about so-called flushable products.)
  • MMSD also has informative information on its Basement Connection Website.